Sail preferably not empty soft drop-down box to select All display values

Method One: sql query does not pass parameters

 

 → → Add template template parameter default parameter values

 

Parameter setting https://www.cnblogs.com/zhuyu139/p/12066574.html

 

 Filter cell formula → IF (len ($ region) == 0, nofilter, $ region)

 

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Method Two: sql query

${if(len(area) == 0,"","and 货主地区 = '" + area + "'")}

 

 sql did a screening operation, drop-down re-set data query